HARRISBURG - An effort to spread the burden for reducing pollution harming the Chesapeake Bay is getting new attention with separate proposals to expand the scope of an existing state program and introduce a different approach.

Pennsylvania established its nutrient trading program to give sewage treatment plant operators and other environmental permit holders another way to meet pollution discharge limits set under the long-term effort to clean up the Chesapeake Bay.

Nutrient trading takes place in an online auction or marketplace where operators of a sewage treatment plant, for example, can purchase credits from farmers and others who have already taken steps to reduce their own nutrient discharges below target levels.

As long as overall pollution controls mandated by the federal Environmental Protection Agency are met, the buying and selling of these credits set at a dollar value per pound is encouraged through the program run by the state Department of Environmental Protection.

The Susquehanna River Basin through its tributaries delivers most of the pollution to the Bay in the form of sediments, nitrogen and phosphorous. Runoff containing these nutrients is responsible for large algae blooms that create "dead zones" devoid of aquatic life.

Therefore, municipalities and businesses throughout the basin are affected by cleanup mandates. The basin encompasses Northeast Pennsylvania except for Monroe, Pike and Wayne counties and slices of Lackawanna and Luzerne counties. Those areas are in the Delaware River Basin.

About 200 municipal sewage treatment plants in the Susquehanna basin face costly upgrades to meet Chesapeake cleanup mandates. The mandates affect agricultural operations and stormwater runoff in urban areas, too.

The largest municipal wastewater treatment systems have access to state loans and grants to finance upgrades, but systems serving small municipalities could find nutrient-trading a cost-effective way to achieve the same goal, said Harry Campbell, executive director of the Chesapeake Bay Foundation's Pennsylvania office, an environmental group.

As an example, the Mount Joy Borough Authority in Lancaster County received credits for nitrogen reduction at its sewage treatment plant by paying a farmer to use environmentally friendly no-till farming on 900 acres of land, according to a DEP document.

Actions taken to help the Bay will improve the thousands of miles of streams in Pennsylvania that are impaired by sediment, nitrogen or phosphorous, said Campbell.

"They first and foremost improve local streams before we see demonstrable impact on the Chesapeake Bay," he said.

DEP recently proposed changes to the trading program designed to improve its process for verifying which pollution-reducing projects are eligible for credits and potentially applying the credit system to urban stormwater. A new state law allows local governments to create stormwater management authorities.

Meanwhile, the Senate is considering a bill that would give incentives to regional manure treatment facilities as a way to reduce nutrient pollution. The measure cleared the Agriculture and Rural Affairs Committee last June.

The bill would introduce competitive bidding to reduce pollution by large-scale agricultural operations, said Sen. Elder Vogel, R-47, Rochester, the sponsor and panel chairman.

The CBF is critical of this legislation, saying it would divert taxpayer money away from more effective methods of controlling farm runoff through creating wildlife habitat and preventing sediment from entering streams.

The Pennsylvania Farm Bureau hasn't taken a position on the bill.

"We believe the legislation has a worthy goal of trying to support efforts to effectively use state resources to provide for agricultural conservation practices that benefit the government," said PFB spokesman Mark O'Neill. "Our concern and question is whether this bill is the best path to accomplish that goal because it doesn't provide any source of funding."